Non-compliant medical balloons for performing angioplasty and other medical procedures are known. U.S. Pat. No. 6,746,425 to Beckham discloses a non-compliant medical balloon and methods for manufacturing the balloon. U.S. Patent Application Publication No. U.S. 2006/0085022 to Hayes et al. discloses a non-compliant medical balloon having an integral woven fabric layer and methods for manufacturing the balloon. U.S. Patent Application Publication No. U.S. 2006/0085023 to Davies, Jr. et al. discloses a medical balloon having strengthening rods and methods for manufacturing the balloon. U.S. Patent Application Publication No. U.S. 2006/0085024 to Pepper et al. discloses a non-compliant medical balloon having an integral non-woven fabric layer and methods for manufacturing the balloon. U.S. Pat. No. 6,746,425 and Publication Nos. U.S. 2006/0085022, US 2006/0085023 and U.S. 2006/0085024 are hereby incorporated herein by reference.
It is desirable to make the outer wall of a non-compliant medical balloon as thin as possible while still maintaining the required pressure rating or burst strength. In non-compliant balloons, the walls typically forms pleats when deflated (i.e., before or after inflation), and these pleats are folded over, wrapped and/or rolled around the long axis of the balloon. The thinner the wall material, the smaller the diameter of the deflated balloon. This smaller diameter facilitates passage of the deflated balloon through narrow vessels, lumens or cavities of the body prior to deployment. The walls of conventional non-compliant balloons include numerous discrete layers and/or components that tend to increase the thickness. A need therefore exists for a medical balloon having thinner walls and/or walls with fewer layers or components.
It is also desirable to make the outer wall of a non-compliant medical balloon as flexible as possible while still maintaining the required pressure rating or burst strength. The flexibility of the deflated balloon directly affects its “trackability,” i.e., its ability to traverse sharp turns or branches of the vessels or body cavities through which the balloon must pass. The more flexible the walls, the better the trackability. The walls of conventional balloons often include physical adhesive layers needed to hold the disparate layers together or to prevent the movement of the wall components relative to one another. Unfortunately, the adhesives, e.g., polyurethanes, used are frequently stiffer than the materials/components being joined. Thus, these adhesive layers may undesirably increase the stiffness of the balloon walls. A need therefore exists for a medical balloon that eliminates or reduces the presence of adhesives in the finished balloon.
Conventional non-compliant balloons may have a wall thickness that varies considerably at different points of the balloon. For example, the wall thickness of the neck portion may be significantly thicker than the wall thickness of the barrel portion. Further, the wall thickness of the cone portion may vary from a relatively large thickness proximate the neck portion to a relatively low thickness proximate the barrel portion. This variation in wall thickness is frequently caused by the incorporation of blow-molded components (which have inherent wall thickness variability) into the structure of the balloon, but may be caused by other factors as well. Regardless of the cause, thicker walls in portions of the balloon that must be folded tend to affect adversely the user's ability to fold the deflated balloon into the desired diameter. This effect may be especially significant in the cone portion, where thicker cone walls can result in “bulges” at the front and the back of the folded balloon that are larger than the intervening barrel portion and, thus, force the user the increase the size of the introducer used to insert the balloon into the patient. It is thus desirable to develop non-compliant balloon construction methods yielding better control over the wall thickness of the balloon at all portions of the envelope. It is further desirable to make non-complaint medical balloons having relatively uniform wall thickness for the entire envelope, including the barrel, cone and neck portions.
It is still further desirable to simplify the construction of non-compliant medical balloons so as to reduce the amount of time and labor required for manufacture, to reduce the product defect rate, and/or to reduce the cost of production. The conventional construction of non-compliant balloons may require many discrete steps, some or all of which may require precision hand assembly that can be difficult or expensive to automate. A need therefore exists for improved methods of manufacturing non-compliant medical balloons.